Did Dow Hit 5,000 Last Week?

Traders cheered Monday when the Dow industrial average went over 5,000 for a few minutes, but using a traditional yardstick--the “theoretical high”--the Dow had already been over 5,000 on Thursday and Friday of last week.

Before the advent of computers, it was virtually impossible to figure out where the Dow index was at any particular moment. So the intraday high (and low) were calculated based on the highest (and lowest) trading prices of each Dow stock over the entire session. These theoretical highs and lows are still appreciated by technicians who want to compare today’s intraday figures to those of decades ago.

But now that computers can keep track of the index level every few moments, the “actual” high and low are the official--and more accurate--measures. The Times publishes theoretical figures in the Daily Diary chart and actual figures in the Market Roundup.